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# why does negative*negative=positive?

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1. yh
2. Any complex number can be written in the form re^i(theta), for negative numbers theta = (2n+1)pi (r is the (positive) magnitude of the negative number)
When you multiply two numbers:
re^i(2n+1)pi*se^i(2m+1)pi = rse^i(2n+2m +2)pi = rse^i(2k)pi
e^ik(2pi) = 1
therefore = rs*1 = rs
no negative sign any more
3. (Original post by ValerieKR)
Any complex number can be written in the form re^i(theta), for negative numbers theta = (2n+1)pi (r is the (positive) magnitude of the negative number)
When you multiply two numbers:
re^i(2n+1)pi*se^i(2m+1)pi = rse^i(2n+2m +2)pi = rse^i(2k)pi
e^ik(2pi) = 1
therefore = rs*1 = rs
no negative sign any more
i still dont understand
4. (Original post by p29)
i still dont understand
uh... because maths
5. (Original post by ValerieKR)
uh... because maths
lel.
6. I think about it this way: Loss of a loss is a gain.
negative * negative is, in a very loose way, loss of a loss.
7. (Original post by ValerieKR)
Any complex number can be written in the form re^i(theta), for negative numbers theta = (2n+1)pi (r is the (positive) magnitude of the negative number)
When you multiply two numbers:
re^i(2n+1)pi*se^i(2m+1)pi = rse^i(2n+2m +2)pi = rse^i(2k)pi
e^ik(2pi) = 1
therefore = rs*1 = rs
no negative sign any more
Two words: learn Latex :P
8. (Original post by oShahpo)
I think about it this way: Loss of a loss is a gain.
negative * negative is, in a very loose way, loss of a loss.
loss-loss=-loss
9. (Original post by oShahpo)
I think about it this way: Loss of a loss is a gain.
negative * negative is, in a very loose way, loss of a loss.
You're thinking of -- =+ rather than (-x)(-y)=xy
10. (Original post by p29)
yh
Because two wrongs always make a right
11. (Original post by SGHD26716)
Because two wrongs always make a right
y
12. Because a double negative = a positive.

'Elephants are grey' = positive
'Elephants are not grey. = negative
Elephants are not not grey.' = double negative = elephants are grey

If something is not not something, then it is that thing. 'Negative' is basically another way of saying 'opposite': imagine the number 2 sees itself in a mirror. The number 2 is 2 units away from zero. The number minus 2 is 2 units away from zero, but in the opposite direction.

So -2*-2 = - - 4, i.e. the opposite of minus 4. The opposite of -4 is 4.
13. (Original post by p29)
loss-loss=-loss
loss-loss=0
14. (Original post by Copperknickers)
Because a double negative = a positive.

'Elephants are grey' = positive
'Elephants are not grey. = negative
Elephants are not not grey.' = double negative = elephants are grey

If something is not not something, then it is that thing. 'Negative' is basically another way of saying 'opposite': imagine the number 2 sees itself in a mirror. The number 2 is 2 units away from zero. The number minus 2 is 2 units away from zero, but in the opposite direction.

So -2*-2 = - - 4, i.e. the opposite of minus 4. The opposite of -4 is 4.
maths=english??
15. (Original post by XOR_)
loss-loss=0
house-house=-house
16. (Original post by p29)
house-house=-house
house-house=emptyland.
17. (Original post by ValerieKR)
You're thinking of -- =+ rather than (-x)(-y)=xy
No I am not. (-2) * (-2) means you lose a loss of 2 twice, which means that you gain 2 twice. Similarly, (2) * (-2) means you gain a loss of two twice, which means you lose 4.
18. (Original post by p29)
yh
If I take away three lots of taking away three, I have 9 more than I would if I hadn't taken away three lots of taking away three.
19. (Original post by XOR_)
house-house=emptyland.
emptyland=-house
20. (Original post by ValerieKR)
If I take away three lots of taking away three, I have 9 more than I would if I hadn't taken away three lots of taking away three.
9 more of what?

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